A lot of people who were good at optimizing games have aged out and/or 'got theirs' and retired early or just got out of the demanding job and secured a better paying job in a sector with more economic upside and less churn. On the other side there's an unending almost exponential group of newcomers into the industry who are believe the hype given by engine makers who hide the true cost of optimimal game making and sell on 'ease'.